Protective relay for tube transmitters



Aug. 1, 1933. F. H..KROGER ,920,646

PROTECTIVE RELAY FOR TUBE] TRANSMITTERS Filed July 18 1929 INVENTOR FRED. H. KROGER ATTORNEY Patented Aug. 1, 1933 UNITED srArss PRQTECTIVE' RELAY FOR TUBE TRANSMITTERS Fred H. Kroger, Ridgewoo d, N. 3., assignor' to Radio Corporation of America, a Corporation of Delaware Application July is, 1929. Serial No. 379,167

3 Claims; (01. 250-17) This invention relates to protective means to be used in radio apparatus and in particular with apparatus in which it is desired to protect one or more circuits from being overloaded or to 5 maintain a constant ratio between the current in one circuit with respect to the current in another circuit. a

Another object of this invention is to provide a device of the above nature inwhich the ratio between currents invarious circuits may be kept constant althoughone of said circuits carries alternating current while the other of said circuits carries direct current;

Briefly and broadly the above objects are obtained by the use of a novel control unit in which two or more wires are arranged in a novel man'- ner such that when current of normal intensity flows in the wires the wires will remain in originalposition, but should a larger amount of current flow in one of the wiresthe wires will, due to the heating effect in the overloaded wire, warp out of positionand close an appropriately lo cated contact in a circuit arranged when so closed to actuate control apparatus forenergising circuits of the radioapparatus, thereby suspending operation of the radio apparatus until flow of current'in the circuits returns to normal. If desired the control apparatus may be arranged to permanently interrupt the energizing circuits, or to interrupt said circuits momentarily until the current in the circuits returns to normal, when the energizing circuits may be automatically closed. i

This invention as will be'obvious can be used for controlling any radio apparatus in general use today as for instance, oscillators in which it is desired to protect a thermionic tube, that is, insure that the anode to cathode alternating current, for instance, bears a definite relation to the 40 current in the anode cathode direct current circuit, and while I do not wish to limitthe'use of my novel invention to any specific apparatus it will be understood that it can be used in any circuits of oscillators, amplifiers repeaters and detectors of any known type today in which a thermionic tube is used. A better understanding of the invention and the operation of the'invention will be had from the following specification and therefrom when read in connection with the annexed drawing in which for purposes of illustration two uses of mynovel invention have been shown.

In the drawing, 'Figure 1 shows a control unit arranged in accordance with my invention;

Figure 2 shows the control unit of Figure 1 applied to a thermionic oscillator;

Figure 3 shows the control device associated with a thermionic amplifier; while,

Figure 4 shows a modification of Figure 1-.

'Referring to the drawing in Figure 1, 1 is a support of insulating material on which is mounted two or more resistance wires 2, 3 of such resistive value that when a predetermined currentflflows through the wires there is no change in the length thereof due to heating, but should the current increase to a valueabove the predetermined value in one of the wires, that wire will increase in length due to theheating eiiect. The wires are conductively connected at i and a contact member 5 is connected by means of an insulating bar or rod 6 to the joint between the wires 2 and 3 and adapted when either of the wires 2 or 3 increases in length to warp or swing toward one of the other of a pair of 'contact points "I and 7a.

Binding posts A, B and C are connected as shown to the free end of 2 the juncture of 2 and 3 and the free end of 3 respectively. The purpose of these posts is to facilitate'connection oi g the unit to the apparatus to be will be pointed out hereinafter. I

The contact 5 is conductively connected through its support or if 5v is supported onan insulator through a wire to connector 9 and thence to a binding post 10. The contacts '7' and 7a are conductivelyconnected to post 58in such a manner that when 5 rests on 7 or 70.

a circuit is formedwhich includes post 8, contact laor 7, contact member 5, flexible lead 9, post 10, a source of energy and a relay winding arranged to control the circuits or a circuit of the thermionic device in any desired manner as, for instance, rendering the circuit or circuits inoperative.

The operation of the unit thus far disclosed is as follows} assuming current to be flowing through 2 and If the current is normal, that is, it is a predetermined value which may be above or below normal current for that circuit under its operating conditions 5 remains at rest position, however, if current in 2 or 3 increases" the length of that wire increases and swings 5 into one of its closed positions, thereby completingthe control circuit. 1

In Figure 2 the novel unit is shown as applied to an oscillator andin particular tothe anode cathode direct current circuit and the anode cathode alternating current circuit thereof in a such a manner as to insure that the ratio of the controlled, as

stant. The oscillation generator comprises a thermionic generator 0 having an oscillation circuit 11, 12 a portion of inductance 11 being connected through condenser 13 to the anode of and through conductor 14 to the cathode of the tube after passing via binding post C, wire 3 of the control unit, and post B to the cathode of 0.

To maintain oscillations in,11, 12 the remain- ,to the control unit shown in Figure 2 except that the resistance wires 2 and 3 are not conductively ing portion of inductance 11 is connected through grid condenser 16 to the grid electrode of 10 and through conductor 14, C, resistance ,wire 3 and post 13 to the cathode of 10. Current in the last named circuit is so little that it, may be disregarded in determining the value of resistance wire 3. The anode potential circuit includes a source of power 17 having one pole. connected (when operating) through a chokecoil 18 to the anode of O and the other pole connected ,via conductor 19 and post A through resistance wire 2 to post B and the cathode of O.

Thus the alternatingcurrent anode cathode circuit is so arranged as to include the anode of the thermionic oscillator O, condenser 13, a portion of inductance 11, conductor, 14, contact C, resistance wire 3, connector 20, contact 13. and the cathode 15 of the oscillation generator 0.

The anode circuit for the spacecurrent includes-source 17. one side of the line from 17 arranged to be opened by a switch 23 described later, choke coil 18 cathode 15 contact B, con nector 20, resistance wire 2, contact'A, and conductor 19 to the other side of source 17;

I The contact points '7, 7a arranged. to be closed by 5 in one of its extreme positions are connected through contact 10 to a source of power 18 in series, when one of the contacts 7 or 7a closes, with a winding 21 arranged as indicated to actuate an armature 22. The armature 22 carries two connectors 23, which are adapted to open the line between the power source 17 and the anode and cathode of the oscillator 0, when the winding 21 is energized by closing of contact 7 or 7a.

In operation if the anode .cathode current through 2 should increase beyond a predetermined value 2 will increase in length. This will swing 5 to the right on the drawing closing contact 7a thereby putting source 18 in series with This will energize 21, withdraw the armature 22 thereby breaking the contacts in the anode, cathode circuit of the oscillation generator. v

The anode space circuit can thenbe leftopen until manually closed, or means as for instance a biasing spring 25 on 22 may be provided to close the contacts 23 when the current in the Wires of the control unit returns to normal.-

In like manner if the alternating current in the anode cathode circuit of 0 increases beyond a predetermined value 3 will increase in length. This will swing 5 to the left closing contact 6 and putting source 18 in series with21 to move the contacts 22 in the open position.

In Figure 3 my novel unit has been shown as applied to an amplifier. In this case the arrangement and the operation are similar to the previous case and a detailed description thereof is not necessary.

In each of the arrangements described above the two circuits which it was desired to control had a common lead so that three contacts A, B and C on'the control unit were sufficient, That is to say, in the previous modification the conductor20 betweenthe juncture 4- of resistance wires 2 and 3 and binding post B is common to both the anode cathode alternating current circuit and the anode cathode direct current circuit. In some cases where it is desirable to maintain a constant ratio between the currents in a pair of circuits which do not have .a connection or a portion in common, an arrangement as illustrated in Figure 4 is necessary.

The control unit shown in Figure 4 is similar coupled together but each terminate in insulating members 2a and 3a respectively which are joined at 4 as inthe previous case. In this manner by providing four binding posts A, E, F and C the two circuits; to be controlled may be completed, 1, to conductor 28 to binding post E, the

a other C, 3, conductor 20b to binding post F. In

this modification the insulating member 6 may be used as shown or may be dispensed with since the operation thereofis thought unnecessary since the operation of said unit and arrangement thereof will be obvious from the brief .description given since it is, except, for the differences pointed out above, similar to the operation andarrangement, of the unit described in Fig-f ure 1. a i

Although for purposes of illustrationI have shown the at present preferred modification of i the control unit and the operation thereof .I do not wish to limit-myself thereby exceptas marked out in the claims attached hereto.

I claim:

1. Protective means to-be used with radio apparatus including a thermionic tube havinga circuit including asource of potential, connected with the output electrodes thereof anda circuit connected with the input electrodes. thereof com:

prising, means for maintaining the ratio of current in said circuits at a predetermined constant the armature '5" may be connected ,wdirectly to 1 value including a thermal element in each of said circuits, said thermal elements each having-one end fixed and the free ends uni-ted physically, by a pivoted element, the position of which depends on the relative length of the element, a pair of circuit closing contacts adjacent said pivoted-element, a switch in said circuitv includingsaid source of potential, and a relay having anarmature connected with said switch and an actuating winding connectedwith said contacts andsaid pivoted element.

2. Protective means to be used with radio apparatus including a thermionic-tube having input and output electrodes and input andoutput; circuits, one of which includes a source of potential connected with said electrodes comprising, means for maintaining the ratio of current in said circuits atv a predetermined-constant value,.said

means including a thermal element in each .of said circuits, said thermal elements each-having one end fixed and the other end united physical- 1y by a pivoted contact closing element, thepositionof which depends on the relative. length of the thermal elements,,,a:pair voi circuitclosing contacts adjacent said pivoted element, a switch in said circuit including said source of potential, a magnetic relay having an armature connected with said switch, and a field winding having one terminal connected through a source of potential with said contacts and the other terminal connected to said pivoted element.

3. In combination with a thermionic tube having an anode, cathode and control electrode, a circuit connected between said control electrode and said cathode, a circuit connected between said anode and said cathode, said last named circuit including a switch and a source of potential, means for disconnecting said source of potential when the ratio between the two currents in said circuits changes from a predetermined value comprising, a thermal element in each of said circuits, each of said thermal elements having one end fixed and theother ends connected together and to a pivoted contact closing element, the whole being arranged so that a change in the ratio of current flowing in said circuits changes the relative length of said thermal elements and causes said pivoted element to move, a magnetic relay having an armature connected to said switch, means for normally biasingsaid armature to a position at which said switch is closed, a magnetic winding associated with said armature, a connection between one terminal of said winding and said pivoted contact closing element, and a source of potential connected between the other terminal of said winding and contacts adjacent said pivoted contact closing element.

' FRED H. KROGER. 

